The present invention relates to magnetic head materials used for magnetic disc devices, VTR and the like and particularly, to a ferromagnetic film having a high saturation magnetic flux density, high permeability, high thermal stability, high corrosion resistance, and reaction resistance and a magnetic head which uses the ferromagnetic film.
Recently, magnetic recording techniques have been remarkably developed and improvement of recording density has been hastened. In order to enhance recording density, it is necessary to use recording mediums of high coercivity and in order to magnetize the recording mediums of high coercivity, magnetic pole materials having a high saturation magnetic flux density are required. Therefore, Ni-Fe alloy (Permalloy) or Co based amorphous alloy thin films have began to be used in place of conventional ferrites as magnetic pole materials. Furthermore, magnetic pole materials are required to have a high permeability in addition to a high saturation magnetic flux density for improvement of read/write efficiency. Moreover, magnetic pole materials are also required to have a thermal stability enough to stand the heating step for filling with glass in the process for the formation of a magnetic head to maintain the high permeability.
As such magnetic pole materials, materials made by the simultaneous addition of Nb, Zr, Ti, Ta, Hf, Cr, W, or Mo and nitrogen to a metal selected from Fe, Co, Ni, and Mn are reported in U.S. Pat. No. 4,836,865. A method for making this material comprises sputtering a metal target having a given composition using a mixed gas of argon and nitrogen as sputtering gas. According to this report, a film having a saturation magnetic flux density of 1.5T and a coercivity of 1 Oe or less has been obtained by alternately laminating a nitrided layer and un-nitrided layer by modulating the nitrogen concentration in the sputtering gas. The coercivity of this film can be kept at a low level until 600.degree. C. and the thermal stability is 600.degree. C.
Furthermore, it is disclosed in MR89-12 (1989. 7) published from The Institute of Electronics, Information and Communication Engineers that a Fe based amorphous film is formed by the simultaneous addition of Ti, Zr, or Hf and C to Fe and then this film is heat treated, thereby to obtain microcrystalline soft magnetic materials having a high thermal stability.